A printed board becomes a finished product after mounting electronic components on it. An electronic component mounting apparatus mounts electronic components on a printed board. On the printed board on which electronic components are to be mounted, a dispenser applies in advance a cream solder, adhesive, or the like. Printed board working apparatuses such as the electronic component mounting apparatus and dispenser can be equipped with a plurality of working heads. The working head of the electronic component mounting apparatus is a suction head including a suction nozzle. The working head of the dispenser is a coating head including a coating nozzle.
A conventional dispenser including a plurality of coating heads is described in, e.g., Japanese Patent No. 3524212. The dispenser disclosed in Japanese Patent No. 3524212 includes a transport device which transports a printed board, and a head unit which moves horizontally above the transport device.
The head unit includes a moving member which moves above the transport device, and a plurality of coating heads arranged on the moving member. Each coating head includes a coating nozzle for applying a coating solution to a printed board. The plurality of coating heads are fixed to the moving member while they are aligned in the transport direction of the transport device.
The head unit moves in the transport direction of the transport device and a horizontal direction perpendicular to the transport direction. By moving the moving member, the coating head is positioned at a target coating position on a printed board. The coating head moves down from the moving member to apply the coating solution from the coating nozzle to the printed board.
The conventional printed board working apparatus including the dispenser disclosed in Japanese Patent No. 3524212 is sometimes operated in a state in which the number of working heads to be used is smaller than a maximum value. The maximum value is the total number of working heads mountable on one head unit. In the printed board working apparatus having a small number of working heads, a working head is added when the number of types of coating solutions is increased or a coating nozzle of a different type becomes necessary.
In the above-described conventional printed board working apparatus, the following problem arises from an increase in the number of working heads. This problem will be explained with reference to FIGS. 15 and 16. A head unit 2 of a working apparatus 1 shown in FIG. 15 includes a moving member 3, first working head 4, and second working head 5. A head unit 2 of a working apparatus 1 shown in FIG. 16 includes a moving member 3, first working head 4, second working head 5, and third working head 6. In FIGS. 15 and 16, reference numeral 7 denotes a transport device; and 8 to 10, printed boards.
A moving device (not shown) supports the moving member 3. The moving device drives the moving member 3 to move above the transport device between the first position indicated by a solid line in each of FIGS. 15 and 16 and the second position indicated by a chain double-dashed line. The movable region of the moving member cannot be changed.
In general, the printed board 8 before work, the printed board 9 to undergo work, and the printed board 10 having undergone work are mounted on the transport device 7. The transport device 7 transports the printed board from right to left in FIGS. 15 and 16.
For convenience, the working apparatus 1 shown in FIG. 15 is illustrated in a state in which the printed board 9 to undergo work falls within a region Z1 where all the working heads 4 and 5 can perform work.
When one working head 6 is added to the left side of the second working head 5 in the working apparatus 1 shown in
FIG. 15, the working apparatus 1 changes to the state shown in FIG. 16. In the working apparatus 1 shown in FIG. 16, a region Z2 where all the working heads 4 to 6 can perform work is positioned locally on the downstream side in the transport direction from the center of the working apparatus 1. This generates a region Z3 where none of the working heads can perform work on the printed board 9 to undergo work.
That is, in the conventional working apparatus, as the number of working heads increases, the region where work can be performed using all working heads becomes narrower.